Generally, PCBs (printed circuit boards) have a structure that includes copper wiring laminated on a plastic board made of epoxy resin, polyimide resin, or phenol resin. In other words, the PCBs (printed circuit board) are used for electrical signal transmission in which a substrate embedded with a copper thin film circuit is coated and installed with various components. However, the conventional electrical PCB has limitations in signal transmission due to failure of the electrical signal transmission capability to catch up with processing capability of parts (electrical elements). Particularly, the electrical signal is sensitive to external environment and generates noises caused by electromagnetic interference to pose a great obstacle to electrical products that require high precisions, thus countermeasures against the noises are needed.
To solve these problems, an optical PCB has been developed using an optical waveguide dispensing with a metal circuit such as a copper in the electrical PCB to enable production of high precision, stable and sophisticated devices robust to electrical wave intervention and noise.
FIG. 1 is a schematic view illustrating a structure of an optical PCB according to prior art, where the optical PCB includes a passive optical element (6) including an active optical element (5) for optical connection, an optical connection block (1) and an optical waveguide (10).
Particularly, a separate PCB (3) for mounting optical transmission and reception elements (5, 6, 7, 8) is formed, where connection of the optical connection block (1) with an optical PCB (4), light emitting and receiving elements (5, 6) is implemented by a guide pin (2).
However, there is a disadvantage in the conventional structure in that noises may occur in a line connecting an electrical signal between a separate PCB (3) and the optical PCB (4), and an alignment error is inevitably generated among the light emitting element (5), the light receiving element (6) and an optical connection block (101), or between the optical connection block (1) and an optical waveguide (210) between the optical connection block (1) and the PCB (4).
Another disadvantage is that detachment or deformation may occur due to vibration or temperature change when a guide pin (202) is used.